Erythromycins are medicines that kill bacteria or prevent their growth.


Erythromycins are antibiotics , medicines used to treat infections caused by microorganisms. Physicians prescribe these drugs for many types of infections caused by bacteria, including strep throat, sinus infections, pneumonia, ear infections, tonsillitis, bronchitis, gonorrhea, pelvic inflammatory disease (PID), and urinary tract infections. Some medicines in this group are also used to treat Legionnaires' disease and ulcers caused by bacteria. These drugs will not work for colds, flu, and other infections caused by viruses.

Drugs in the erythromycin group may be used to eliminate such areas of infection as abscesses prior to surgery. For this purpose, they have been used in dentistry, eye surgery, and intestinal surgery. In some cases, erythromycin has been used to treat brain abscesses.


The drugs described here include erythromycins (Erythrocin, Ery-C, E-Mycin, and other brands) and such medicines that are chemically related to erythromycins as azithromycin (Zithromax) and clarithromycin (Biaxin). They are available only with a physician's prescription and are sold in capsule, tablet (regular and chewable), liquid, and injectable forms.

Recommended dosage

The recommended dosage depends on the type of erythromycin, the strength of the medicine, and the medical problem for which it is being taken. The person should check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.

The patient must always take erythromycins exactly as directed. The patient should never take larger, smaller, more frequent, or less frequent doses. To make sure the infection clears up completely, it is very important to take the medicine for as long as it has been prescribed. Patients must not stop taking the drug just because symptoms begin to improve. This is important with all types of infections, but it is especially important in streptococcal infections, which can lead to serious heart problems if they are not cleared up completely.

Erythromycins work best when they are at constant levels in the blood. To help keep levels constant, the medicine should be taken in doses spaced evenly through the day and night. The patient must not miss any doses. Some of these medicines are most effective when taken with a full glass of water on an empty stomach, but they may be taken with food if stomach upset is a problem. Others work equally well when taken with or without food. Patients should check package directions or ask the physician or pharmacist for instructions on how to take the medicine.


There are warnings and cautions that apply to erythromycin and its related drugs when they are taken by mouth over a period of several days. These warnings may not apply when erythromycin is given intravenously (by vein), or as a single dose prior to or immediately after surgery.

Symptoms should begin to improve within a few days of beginning to take this medicine. If they do not, or if they get worse, the patient should check with the physician who prescribed the medicine.

Erythromycins may cause mild diarrhea, which usually goes away during treatment. Severe diarrhea, however, could be a sign of a very serious side effect. Anyone who develops severe diarrhea while taking erythromycin or related drugs should stop taking the medicine and call a physician immediately.

Special conditions

Taking erythromycins may cause problems for people with certain medical conditions or people who are taking certain other medicines. Before taking these drugs, the patient should tell the physician about any of these conditions.

ALLERGIES. Anyone who has had unusual reactions to erythromycins, azithromycin, or clarithromycin in the past should let the physician know before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

PREGNANCY. Some medicines in this group may cause problems in pregnant women and have the potential to cause birth defects. Women who are pregnant or who may become pregnant should check with their physicians before taking these drugs.

BREASTFEEDING. Erythromycins pass into breast milk. Mothers who are breastfeeding and who need to take this medicine should check with their physicians.

OTHER MEDICAL CONDITIONS. Before using erythromycins, people with any of these medical problems should make sure their physicians are aware of their conditions:

USE OF CERTAIN MEDICINES. Taking erythromycins with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

Side effects

The most common side effects are mild diarrhea, nausea, vomiting, and stomach or abdominal cramps. These problems usually go away as the body adjusts to the drug and do not require medical treatment. Less common side effects, such as sore mouth or tongue and vaginal itching and discharge also may occur. They do not need medical attention unless they persist or are bothersome.

More serious side effects are not common, but may occur. If any of the following side effects occur, the patient is advised to check with a physician immediately:

Although rare, very serious reactions to azithromycin (Zithromax) are possible, including extreme swelling of the lips, face, and neck; and anaphylaxis (a violent allergic reaction). Anyone who develops these symptoms after taking azithromycin should stop taking the medicine and get immediate medical help.

Other rare side effects may occur with erythromycins and related drugs. Anyone who has unusual symptoms after taking these medicines should get in touch with the physician.


Erythromycins may interact with many other medicines. When an interaction occurs, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes erythromycins should let the physician know all other medicines he or she is taking. The drugs that may interact with erythromycins include:

The list above does not include every drug that may interact with erythromycins. A physician or pharmacist should be consulted before combining erythromycins with any other prescription or nonprescription (over-thecounter) medicine.



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"Erythromycin." Medline Plus Drug Information. [cited May 2003) .

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Nancy Ross-Flanigan Sam Uretsky

User Contributions:

i have soreless blister on my penis, my penis itch inside & i have visited a clinic & was given erythromycins. Can it cure this STI.?

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